Physical Mechanism of AdS Instability and Universality of Holographic Thermalization

Gravitational falling in the Anti-deSitter Spacetime (AdS) has two characteristic properties: i) A thick shell becomes a thin shell. ii) Any shape become spherical. Such a focusing character of the AdS space, for collapse of dust clouds, leads to the rapid thermalization mechanism in strongly interacting system. For a conformally flat boundary, we show that such focusing mechanism is universal in all known background geometries of D-branes as well as in those of AdS spacetime. We calculate the time scale for thermalization in terms of the total mass density and the lowest upper bound of the energy distribution of the initial particles. We find t(th) similar to (1 - c(1)/E-2)(1/2)/T, which is less than the typical collision time so that softer modes thermalize first. We also suggest that the same idea can shed light on the collapse of waves belonging the heavy numerical relativity.